114 
Psyche 
une 
THE WORKING HOURS OF ANTS. 
By Ernest Seeman, 
Duke University. 
During the summer of 1927 the writer observed the periods 
of activity of two species of ants in North Carolina, and was 
surprised to find that one species, at least, continues to work 
throughout the night and, to some extent, during rains. The 
detailed observations may be summarized as follows: 
July 22-A caravan, Crematogasier lineolata (Say), was moving 
back and forth from a nest, located between the flooring and 
sub-flooring of a porch, to the topmost branches of a maple tree, 
where a colony of aphids were being milked for honey-dew. 
The distance traversed was about 40 feet. The workers leaving 
the nest carried sand and bits of dried mortar from crumbling 
masonry; those moving in the opposite direction evidently 
transported honey-dew. The sand and debris were being used 
to build a shelter over the aphids. The column was actively 
moving when first observed at 4 p. m., and at 11 p. m., two hours 
after dark, appeared undiminished in numbers and activity. 
The average speed of the workers was about two feet per minute, 
which enabled them to cover 5i feet or, one “ant-mile,” 1 
15 minutes being required to traverse the entire route of 
40 feet. Thus an individual was traveling 360 ant-miles in a 
12-hour period, if no time be deducted for loitering. As it is 
apparent from the observations below that ants may work not 
only 12 hours at a stretch, but for much longer periods, it will be 
seen that they possess great energy. 
Between 11 p. m. and 3:30 a. m. of July 22 a thundershower 
occurred, abating by the latter hour. At that hour the ants’ 
route was drenched with water, but the ants were found to be 
working in as large numbers and in as compact order as during 
the previous afternoon. About half their route ran underneath 
a floor, the remaining half extending across clay-covered ground 
x An “ant-mile” is a convenient unit of measurement obtained by com- 
paring the length of an ant’s body with that of a man’s in relation to a mile. 
